Earth Resistance

IEEE SA - 81-1983 - IEEE Guide for Measuring Earth ...

Ask Google.

You may want to rethink the second question.

You might also want to find out if the application or owner have more stringent requirements. I have run across a requirement to provide a 2 ohm or less resistance for comm buildings and DC substations based on customer requirement.

Can you share the link please? Such standards are not easily available on the internet.

We required this for audit purposes.

Thanks

You probably need a copy of BS7671. You can get it from on-line retailers by carrying out a search.

You might want to read the article in Wikipedia on Earthing Systems. An IT system, in the limit, has an infinite earth resistance.

You might want to talk to a qualified Electrician near you. There are dozens in the phone book.

But, alas and alack, electricians require a tariff for imparting their knowledge on the unknowing.

The minimum value is zero ohms.

That's called 'throwing your intellectual weight around"...keep it under the cap gendarme !

Baaahhh its just a Zero!

I would confer with your authority having jurisdiction (AHJ) and/or your facility engineer. My facility requirement is less than 1 ohm in a single point ground configuration. Many facilities have stringent requirements which can differ widely across different configurations.